vol. 29, no. 2, pp. 141–147, 2008
Zinc accumulation in lichens due to industrial emissions
around Vorkuta, northeast European Russia
Tony R. WALKER
School of Biology, University of Nottingham, Nottingham, NG7 2RD, UK;
Dillon Consulting Limited, 137 Chain Lake Drive, Halifax, Nova Scotia, B3S 1B3, Canada
<tonyrobertwalker@gmail.com>
Abstract: Zinc concentrations in apices [Zn 2+]apex of the lichens, Cladonia arbuscula and
C. rangiferina were determined along transects through two sub−Arctic towns in the Usa
River Basin, northeast European Russia. One transect, which was 130 km long running in
an east−west direction, passed through the town of Vorkuta and the other transect, which
was 240 km long running in a southwest−northeast direction, passed through Inta. Zinc ac−
cumulation in lichens, which was detected 25–40 km within the vicinity of Vorkuta, was
largely attributed to local emissions of alkaline coal ash from coal combustion. The present
results using C. arbuscula around Vorkuta are consistent with those of previous studies sug−
gesting that this lichen is a useful bioindicator for trace metals. There was no such elevation
of [Zn 2+]apex detected in C. rangiferina along the transect running through Inta.
K e y w o r d s : Arctic, atmospheric deposition, zinc, lichens, bioindicators, Cladonia arbus−
cula, Cladonia rangiferina.
Introduction
Russia is the principal contributor of metal emissions in Europe and has the
most extensive industrial developments north of the Arctic Circle including the
mining and metallurgical industries of Norilsk in Siberia and Monchegorsk on the
Kola Peninsula (Toutoubalina and Rees 1999; Reimann et al. 2000). By compari−
son, north−eastern European Russia has suffered less from industrial pollution
and large areas remain unpolluted, although some locations bear the signs of local
en− vironmental degradation, such as changes in community structure of
vegetation around the coal mining town of Vorkuta (Virtanen et al. 2002).
Exploitation of coal here began in the 1930s and intensified until the 1990s
when extraction de− clined owing to increased transportation costs and poor
combustion qualities of the coal (Hill 2000). Vorkuta is the centre of the coal
industry with six mines operating during the period of this research in 1999
whereas Inta had fewer operating mines
Pol. Polar Res. 29 (2): 141–147, 2008
142
Tony R. Walker
in 1998 and a comparatively smaller coal mining industry. Coal mining and com−
bustion for power generation have been the principal sources of heavy metal pollu−
tion in the region; with Vorkuta being the highest emitter and suffering a legacy of
pollution impacts resulting from the deposition of alkaline fly ash (Solovieva et al.
2002; Walker et al. 2003a, b; Walker 2005). An inventory of pollutants emitted
from both towns has been summarized by Solovieva et al. (2002).
Mat−forming terricolous lichens are important components of plant communi−
ties in high latitudes, where they contribute to nutrient cycling and secondary pro−
duction, such as grazing (Longton 1997). Lichens are primarily dependant on at−
mospheric sources for nutrients and therefore readily accumulate atmospheric
contaminants, such as metals (Nash and Gries 1995). Therefore, they are amongst
the most pollution sensitive receptors in terrestrial ecosystems (Richardson 1988).
Spatial variation in the chemical composition of lichens has been widely used to
monitor environmental quality as a result of industrial activities including situated
around coal−fired power stations (Gonzalez and Pignata 1997; Walker and Pystina
2006; Walker et al. 2006a). The principle source of electrical power used in the
town in this study is generated by coal−fired power stations.
The present research aimed at assessing the extent of zinc deposition due to lo−
cal sources around Vorkuta and Inta in the Komi Republic, northeast European
Russia using the lichens Cladonia arbuscula and C. rangiferina along a transect
passing through both towns. This region spans the sub−Arctic taiga forest and tun−
dra ecotones and has already been identified as a significant source of metal emis−
sions mainly as a result of coal fired power stations in the towns of Vorkuta and to
a lesser extent Inta (Solovieva et al. 2002; Walker et al. 2003a, b; Walker 2005;
Walker et al. 2006b). The study provided an opportunity to further evaluate the use
of terricolous lichens as bioindicators of metal deposition (Walker et al. 2003b,
2006a).
Materials and methods
Transects for sampling lichens were establishe d that passed through the towns of
Vorkuta (67 30’N, 64 05’E) and through Inta (66 03’N, 60 10’E). Inta was chosen
for the second transect study because it also has a large coal industry and is currently
the second most largest coal producing town in the region. These sampling locations
and transects have been illustrated and described in greater detail elsewhere (see
Fig. 1; Walker et al. 2003a, b). The transect passing through Vorkuta was approxi−
mately 130 km long and oriented west−east; characterized by Betula nana L. shrub
tundra along its entire length. The transect passing through Inta was 240 km long and
oriented southwest−northeast spanning taiga forest and tundra ecotones. Mean an−
nual precipitation for Vorkuta and Inta is 518 and 473 mm respectively and south
westerly winds prevail in the region.
Zinc accumulation in lichens
143
Fig. 1. Pechora region showing sampling transects through the towns of Vorkuta and Inta.
Six sampling sites were selected along each of the transects. Originally nine
sampling sites had been chosen along the Inta transect (reflecting its greater
length) but the availability of C. rangiferina along this transect was limited partly
due to the lack of suitable lichen heath habitat in the area. At each site, three
sub−sites were selected, 1 km apart, at which six replicate samples of lichen were
collected at distances 10–20 m apart in open areas in order to minimize tree canopy
effects; these were usually inter−tree positions in open forest, or in tundra. Most
sites were in wilderness areas remote from roads. Terricolous mat−forming lichens
C. arbuscula (Wallr.) Flot. and C. rangiferina (L.) F.H.Wigg. were collected at
sub−sites to provide biomarkers for atmospheric deposition and because of their
abundance in shrub tundra and taiga forest. Lichen samples were air−dried in the
field, sealed in LDPE containers and stored at 4 C until analysis. Powder−free
LDPE gloves were worn when handling lichens in the field and the laboratory to
minimise contamination. Lichens were rehydrat ed overnight by exposure to wa−
ter−saturated air (over water in a desiccator) at 4 C, then fully saturated by spray−
ing lightly with deionised water and cleaned of extraneous debris using forceps.
Samples were dried overnight at 80 C and then weighed, where c. 100 mg of api cal
(5 mm) tissue was digested to dryness in 1 mL of concentrated HNO3 at 175 C.
The residue was dissolved in 10 mL 1 M HNO3 and appropriate quantities of ionis−
ation suppressant and releasing agent (CsC12, LaC12) added. Zinc was selected be−
cause it was one of several trace metals found to contaminate snow and soils lo−
144
Tony R. Walker
cally in the survey region (see Walker et al. 2003a; Walker 2005) and was mea−
sured by flame atomic absorption spectrophotometry (FAAS); concentrations
were recalculated in relation to the mass of dried apical lichen tissue to allow direct
comparison with the solution data (see Walker et al. 2003b).
Genstat and Minitab were used to perform standard statistical analyses
(ANOVA, correlation analysis and linear regression).
Results and discussion
Collections of C. arbuscula was complete at all six sites along the Vorkuta
transect despite mat−forming lichen cover being generally poor in the region due to
heavy grazing and trampling by reindeer (Crittenden 2000). Along the Inta
transect collections of C. rangiferina were made as C. arbuscula was less abun−
dant along this transect. Whilst no attempt was made to compare absolute concen−
trations between the two lichen species they were chosen based on their availabil−
ity along each transect. Therefore the results of this study may be used as a proxy
for indicating localized perturbations of Zn concentrations. There was significant
localized higher [Zn2+]apex in C. arbuscula in the vicinity of Vorkuta (P <0.001).
For example the highest concentration of [Zn2+]apex in C. arbuscula were found at
the two sites closest to the town (see Fig. 2a). Previous studies found no such local−
ized elevated concentrations in [Zn2+]apex in C. stellaris around Inta, but it was
strongly related to latitude (Walker et al. 2003b). It is possible that the apparent
lack of any Zn perturbation around Inta may be due to lower sampling density
T ab le 1
2+
Comparison of [Zn ]apex (μg g−1) in Cladonia spp. from high latitude industrial and pristine
areas. Grey shading indicates industrial areas
Vorkuta (Transect) (coal mining)
Inta, NE European Russia (coal mining)
Inta, NE European Russia (coal mining)
[Zn]
−1
(μg g )
C. arbuscula 16–55
C. rangiferina 15–34
C. stellaris
9–32
Gusum, Sweden (steel foundry)
C. rangiferina
Location
SE Ohio, USA (coal mining)
Ontario, Canada, Uranium mines
(0.5–30 km)
Delaware Gap, USA (zinc smelter)
Northwest Territories, Canada
Northwest Territories, Canada
Bellsund area, Spitsbergen
High Point Park, New Jersey, USA
Species
Cladonia sp.
Study
This study
This study
Walker et al. (2003b)
Folkeson and
55–75
Andersson−Bringmark (1988)
27–42 Lawrey and Rudolf (1975)
C. mitis
13–22
Fahselt et al. (1995)
Cladonia sp.
Cladonia sp.
Cladonia sp.
Cladonia sp.
C. rangiferina
61–80
7–55
16–25
29–39
7–16
Nash (1975)
Puckett (1978)
Puckett and Finegan (1980)
Jóźwik (1990)
Glenn et al. (1991)
145
Zinc accumulation in lichens
a
0.9
W
E
0.8
0.7
0.6
Vorkuta
0.5
0
20
40
60
80
100
120
140
Distance (km)
b
0.4
N
S
0.3
Inta
0.2
0
50
100
150
200
250
Distance (km)
Fig. 2. Variation in [Zn 2+]apex in Cladonia arbuscula ( ) along the transect passing through Vorkuta
(a) and C. rangiferina ( ) along the transect passing through Inta (b). Plotted values are means ±1 SE
(n = 18). Note the different scales used for both plots.
along this transect, although local collections of C. rangiferina were attempted,
their availability was scarce. Despite the lower sampling density along the Inta
transect collections of C. rangiferina around Inta (Fig. 2b) did not show an appar−
ent relationship between [Zn2+]apex and latitude unlike collections of C. stellaris in
a previous study (Walker et al. 2003b). Variation in [Zn2+]apex in C. arbuscula
around Vorkuta correlates well with other pollution signals from earlier work re−
lating to snow ([SO42−]snow, [Ca2+ ]snow, [K+]snow, pH); metal contamination in soil
and [N]apex in lichens (r = 0.90, P <0.01, n = 6) (Walker et al. 2003a, b).
The concentration ranges presented in Table 1 are in broad agreement with
previous studies but any discrepancies may reflect physiological differences be−
tween lichens or method of analyses. Therefore, it was not the intent of this study
to make direct inter comparisons of Zn concentrations between different species
but rather to use Zn concentrations in lichens as a proxy to detect elevated levels
around industrial sites. The lowest concentrations of [Zn2+]apex were comparable
with other studies in pristine locations (see Table 1), whilst elevated concentra−
146
Tony R. Walker
tions around Vorkuta in this study were as high as concentrations found in other
Cladonia spp. around coal mining towns (Walker et al. 2003b; Lawrey and Rudolf
1975). According to Folkeson and Andersson−Bringmark (1988), [Zn2+]apex mea−
sured in C. rangiferina sampled 6–7 km away from steel foundries in Gusum,
Sweden were 55–75 μg g−1 whilst the first indication of a reduced ground cover for
this lichen species was only observed when the [Zn2+]apex exceeded 500 μg g−1.
Therefore, they suggested that a [Zn2+]apex limit of 600 μg g−1 would indicate the ap−
parent critical threshold concentration (fatal concentration) for survival of C.
rangiferina. The [Zn2+]apex observed around Vorkuta in this study fall far below the
thresholds reported by Folkeson and Andersson−Bringmark (1988) and the con−
centrations reported here are therefore likely not to cause damage to these lichens.
Terricolous mat−forming lichens are abundant throughout the sub−Arctic tun−
dra and taiga regions and are sentinel species that readily accumulate contaminants
that reflect local environmental conditions due to their slow growth and physiol−
ogy. The present results using C. arbuscula around Vorkuta are consistent with
those of previous studies suggesting that they are useful bioindicators for trace
metals. While there occurs a clear Zn peak in the town of Vorkuta, Inta is not
marked by a Zn anomaly. The anthropogenic Zn peak in C. arbuscula around
Vorkuta is attributed to local deposition of coal ash from coal combustion extend−
ing 25–40 km around Vorkuta.
Acknowledgements. — This investigation was a contribution to TUNDRA (TUNdra Deg−
radation in the Russian Arctic) supported by the Environment and Climate Programme of the
European Commission (contract ENV4−CT97−0522). We are grateful to our Russian colleagues
at the Komi Science Centre, Institute of Biology, Syktyvkar and Peter Kuhry for co−ordinating
the project.
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Received 21 April 2008
Accepted 19 May 2008